Glial fibrillary acidic protein as an early marker of hepatic stellate cell activation in chronic and posttransplant recurrent hepatitis C

Abstract

Activated alpha-smooth muscle actin (alpha-SMA)-positive hepatic stellate cells (HSCs) are pericytes responsible for fibrosis in chronic liver injury. The glial fibrillary acidic protein (GFAP), commonly expressed by astrocytes in the central nervous system, is expressed in vivo in the liver in a subpopulation of quiescent stellate cells. In the rat, increased GFAP expression in the acute response to injury and down-regulation in the chronic response have been observed, whereas reports concerning GFAP expression in human liver are still conflicting. We investigated the utility of GFAP compared to alpha-SMA as an immunohistochemical marker of early activated HSCs in chronic and posttransplant recurrent hepatitis C and correlated GFAP expression with vascular remodeling and fibrosis progression. With immunohistochemistry and a semiquantitative scoring system, the expression of GFAP and alpha-SMA in HSCs and the microvessel density were analyzed in biopsies from normal livers obtained from cadaveric donors [donor liver (DL); n = 21] and from livers from posttransplant hepatitis C virus recurrent hepatitis (HCV-PTR) patients (n = 19), hepatitis C virus chronic hepatitis (HCV-CH) patients, (n = 12), and hepatitis C virus cirrhosis (HCV-C) patients (n = 16). The percentage of alpha-SMA-positive HSCs was significantly higher in the HCV-PTR, HCV-CH, and HCV-C groups compared to the DL group (P < 0.01). The percentage of GFAP-positive HSCs was significantly higher in the HCV-PTR group compared to the DL, HCV-C (P < 0.01), and HCV-CH (P < 0.05) groups and in the HCV-CH group compared to the DL group (P < 0.01), inversely correlating with the extent of fibrosis and microvessel density (P < 0.01). In the HCV-PTR group, the percentage of GFAP-positive HSCs correlated with fibrosis progression (P < 0.01). In conclusion, GFAP could represent a useful marker of early activation of HSCs in HCV-CH and seems to predict fibrosis progression in HCV-PTR.